Systems and methods to enhance passivation integrity

ABSTRACT

A semiconductor device having enhanced passivation integrity is disclosed. The device includes a substrate, a first layer, and a metal layer. The first layer is formed over the substrate. The first layer includes a via opening and a tapered portion proximate to the via opening. The metal layer is formed over the via opening and the tapered portion of the first layer. The metal layer is substantially free from gaps and voids.

REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.13/974,400 filed on Aug. 23, 2013, the contents of which areincorporated by reference in their entirety.

BACKGROUND

Semiconductor device fabrication is a process used to create integratedcircuits that are present in everyday electrical and electronic devices.The fabrication process is a multiple-step sequence of photolithographicand chemical processing steps during which electronic circuits aregradually created on a wafer composed of a semiconducting material.Silicon is an example of a typical semiconductor material used in thefabrication process, however other types of semiconductor materials canbe utilized.

One layer often used in semiconductor devices is a passivation layer.Passivation layers are formed over other layers in order to protect theunderlying layers from other materials utilized in the fabricationprocess, including solutions, gases, plasmas and the like. Any unwantedgaps or holes in passivation layers can result in damage to underlyinglayers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating an example semiconductor devicefabrication system.

FIG. 2 is a flow diagram illustrating a method using a tapered profileand modulation bars/spacers to enhance passivation integrity.

FIG. 3A is a top view of masks that can be utilized to fabricate thesemiconductor device with enhanced passivation coverage for a conductivevia.

FIG. 3B is a cross sectional view of the semiconductor device fabricatedusing the method.

FIG. 3C is a cross sectional view of the semiconductor device afterpatterning the hardmask layer.

FIG. 3D is a cross sectional view of the semiconductor device after ataper etch of the hard mask layer.

FIG. 3E is a cross sectional view of the semiconductor device afterformation of a metal layer.

FIG. 3F is a cross section view of the semiconductor device having alayer of photoresist covering a via portion of the metal layer.

FIG. 3G is a cross sectional view of the semiconductor device afterpatterning the metal layer.

FIG. 3H is a cross sectional view of the semiconductor device afterformation of another passivation layer.

FIG. 4 is a flow diagram illustrating a method utilizing a modulationspacer to increate a step angle and enhance passivation layer coveragerate.

FIG. 5A is a cross sectional view of a semiconductor device fabricatedusing the method.

FIG. 5B is a cross sectional view of the semiconductor device afterformation of a thin film over the device.

FIG. 5C is a cross sectional view illustrating the semiconductor deviceafter formation of modulation spacers.

FIG. 5D is a cross sectional view of the semiconductor device afterformation of a metal layer.

FIG. 5E is a cross sectional view of the semiconductor device afterpatterning the metal layer.

FIG. 5F is a cross sectional view of the semiconductor device afterformation of a second passivation layer.

DETAILED DESCRIPTION

The description herein is made with reference to the drawings, whereinlike reference numerals are generally utilized to refer to like elementsthroughout, and wherein the various structures are not necessarily drawnto scale. In the following description, for purposes of explanation,numerous specific details are set forth in order to facilitateunderstanding. It may be evident, however, to one skilled in the art,that one or more aspects described herein may be practiced with a lesserdegree of these specific details. In other instances, known structuresand devices are shown in block diagram form to facilitate understanding.

Generally, semiconductor fabrication involves performing a relativelylarge number or process steps on a wafer or semiconductor material inorder to produce a desired semiconductor integrated circuit. Thefabrication process is a multiple-step sequence of photolithographic andchemical processing steps during which electronic circuits are graduallycreated on a wafer composed of a semiconducting material.

The process steps can be broken down into front end of line (FEOL)processing and back end of line (BEOL) processing. In one example, over300 sequenced process steps are required to form an integrated circuiton a semiconductor wafer.

FIG. 1 is a block diagram illustrating a semiconductor devicefabrication system 100. The system 100 can be utilized to remove nitriderelated precipitate from semiconductor devices during fabrication. Theremoval process utilizes phosphoric acid.

The system 100 includes a process tool 104 and a control component 106.The system operations on a semiconductor device or wafer 102. Thesemiconductor device 102 includes an oxide layer.

The process tool 104 can include one or more tools, temperaturechambers, and the like that are utilized in semiconductor fabrication.The control component 106 initiates a process to enhance passivationcoverage. In one example, the process utilizes modulation bars and atapered hard mask to improve gap fill. In another example, the processuses a taper or step angle to enhance passivation coverage. Additionaldetails are described in the methods below.

FIG. 2 is a flow diagram illustrating a method 200 using a taperedprofile and modulation bars/spacers to enhance passivation integrity. Ahardmask layer is formed with a tapered profile and modulation barsprior to forming a metal layer. As a result, voids and the like in themetal layer are mitigated. Thus, a passivation layer can be formed overthe metal layer with improved coverage. The method 200 mitigates gaps orholes in passivation layers, enhances coverage and, as a result,protects underlying layers.

The method 200 is described in conjunction with FIGS. 3A to 3H in orderto facilitate understanding. However, it is appreciated that the extrafigures are provided for illustrative purposes and are not intended tolimit the method 200 to the arrangements shown therein. FIGS. 3A to 3Hdepict a semiconductor device fabricated using the method 200.

FIG. 3A is a top view of masks 318 that can be utilized to fabricate thesemiconductor device with enhanced passivation coverage for a conductivevia. The masks 318 are utilized to form modulation bars within ahardmask layer, as shown below. The masks exhibit a larger corner angleat 320 to improve coverage rate. The masks also show and define amodulation bar length ‘L’ and a via hole width ‘b’.

A semiconductor device having a substrate, a first passivation layer,and a hardmask is provided at block 202. The substrate can include oneor more layers and/or structures. The substrate includes a TME layer.The first passivation layer is formed over or on the substrate. Thefirst passivation layer is comprised of a passivation material, such assilicon nitride, silicon dioxide, and the like. The first passivationlayer can be formed by a suitable deposition process, such as chemicalvapor deposition, plasma enhanced chemical vapor deposition, and thelike. The hardmask layer is formed over or on the first passivationlayer.

FIG. 3B is a cross sectional view of the semiconductor device fabricatedusing the method 200. The device is described as an example forillustrative purposes.

The device includes a substrate 302 having a TME layer 304 formedtherein. A first passivation layer 306 is formed over the substrate 302.Additionally, a hardmask layer 308 is formed over the first passivationlayer 306.

The hardmask layer is patterned at block 204 to form a via opening andmodulation bar openings. The via opening exposes a portion of theunderlying layer, the first passivation layer. The modulation baropenings expose modulation portions.

FIG. 3C is a cross sectional view of the semiconductor device afterpatterning the hardmask layer. The hardmask layer 308 has been patternedas described at block 204. The hardmask 308 includes a via opening 322and modulation bar openings 320.

A taper etch is performed at block 206 in order to taper portions of thehardmask layer. The taper etch is performed at an angle such thatportions closes to a via region are etched more than those further away.The taper etch uses modulate spacers and etch loading. The taper etchdefines a tapered portion or ladder shaped film behavior; including ataper angle, via width, and a via height for the hardmask layer.

FIG. 3D is a cross sectional view of the semiconductor device after ataper etch of the hard mask layer. The hardmask layer 308 was previouslypatterned at block 204. Here, the taper etch of block 206 forms taperedportions of the hardmask layer 308. The tapered portion is also referredto as a ladder shaped film. The taper etch defines a taper angle 312,which is greater than 90 degrees, and in another example, is greaterthan about 100 degrees. The taper angle 312 plus the angle 310 equal 180degrees.

The taper etch also defines the via width ‘b’ and the via height ‘a’ forthe hard mask layer. A spacing distance S of the modulation bars isshown as ‘S’. A width of the modulation bars is shown as ‘W’. Theseportions are identified in FIG. 3D.

An aspect ratio is defined as b/a, which in one example ranges fromabout 2 to 5. The via hole width ‘b’ is greater than or equal about 2 umin one example. The number of hardmask spacers, also referred to asmodulation bars is greater than or equal 1. The space S in one exampleis greater than or equal to about 0.5 um. The width W of the modulationbars is greater than or equal to about 0.5 um. It is noted that the Sand W can vary from each other. A modulation bar length ‘L’, shown inFIG. 3A, is within a range of about 0.5 um to about 2 um, in oneexample.

A metal layer is formed over the device at block 208. The metal layer isformed by a suitable metal deposition process, such as sputtering, andthe like. The metal layer includes a metal material, such as AlCu, inone example. The modulation bars and tapered portions of the hardmasklayer facilitate forming the metal layer properly, in particular withina via region.

FIG. 3E is a cross sectional view of the semiconductor device afterformation of a metal layer. The metal layer 314 is shown formed over thedevice. In this example, the metal layer 314 is comprised of AlCu. Itcan be seen that portions of the metal layer 314 extend through thehardmask 308 modulation bars and the first passivation layer 306 anddown to the underlying substrate 302 and the TME 304.

The metal layer is patterned using a layer of resist to form aconductive via at block 210. A layer of resist is formed and utilizedwith a suitable patterning process to remove portions of the metallayer. The remaining portion forms the conductive via. A suitable metalpatterning process is utilized. It is appreciated that other suitablepatterning processes can be utilized.

FIG. 3F is a cross section view of the semiconductor device having alayer of photoresist covering 316 a via portion of the metal layer 314.

FIG. 3G is a cross sectional view of the semiconductor device afterpatterning the metal layer 314. The remaining portion of the metal layer314 is a conductive via. The layer of resist 316 has also been removed.

A second passivation layer is formed over the device at block 212. Thesecond passivation layer is also comprised of a suitable passivationmaterial, such as silicon nitride, silicon dioxide, and the like. Thepassivation layer forms over the conductive via with a suitable orenhanced coverage rate. As a result, the passivation layer protects theunderlying layers, including the conductive via.

In contrast, other techniques to form such passivation layers overconductive vias are problematic. The use of the modulation bars andtapered portions mitigate creation of voids or gaps within theconductive via. The voids or gaps prevent proper formation of thepassivation layer and permit damaging of underlying layers.

FIG. 3H is a cross sectional view of the semiconductor device afterformation of another passivation layer. Here, a second passivation layer317 is formed over the semiconductor device. It can be seen that thesecond passivation layer 317 covers all or substantially all portions ofthe remaining metal layer 314.

It is appreciated that variations in the method 200 are contemplated.The number, size and shape of hardmask modulation bars and the taperangle can vary. Further, additional blocks and/or processes can also beperformed.

FIG. 4 is a flow diagram illustrating a method 400 utilizing amodulation spacer to increate a step angle and enhance passivation layercoverage rate. The method 400 utilizes a modulation spacer prior toforming a metal layer to mitigate gaps and/or voids in the metal layer.Thus, a passivation layer formed over the metal layer has improvedcoverage and gaps in the passivation layer are mitigated.

The method 400 is described in conjunction with FIGS. 5A to 5F in orderto facilitate understanding. However, it is appreciated that the extrafigures are provided for illustrative purposes and are not intended tolimit the method 400 to the arrangements shown therein. FIGS. 5A to 5Fdepict a semiconductor device fabricated using the method 400.

The method begins at block 402, wherein a semiconductor device isprovided. The device includes a substrate, a TME layer, and a firstpassivation layer. The substrate can include one or more layers and/orstructures. The substrate includes a TME layer. The first passivationlayer is formed over or on the substrate. The first passivation layer iscomprised of a passivation material, such as silicon nitride, silicondioxide, and the like. The first passivation layer can be formed by asuitable deposition process, such as chemical vapor deposition, plasmaenhanced chemical vapor deposition, and the like. A portion of thepassivation layer overlying the TME layer is removed.

FIG. 5A is a cross sectional view of a semiconductor device fabricatedusing the method 400. The device is provided as an example in order tofacilitate understanding. It is appreciated that other variedsemiconductor devices are contemplated.

The device is provided as described in block 402. The device includes asubstrate 502, which has a TME layer 504 formed therein. A firstpassivation layer 506 is formed over the substrate 502. It has anopening over at least a portion of the TME layer.

A thin film is formed over the device at block 404. The thin film has anetch rate varied from the first passivation layer. In one example, thethin film has a selective etch rate between the film and the firstpassivation layer larger than 1. In another example, the thin film isformed with a thickness of about 0.6 um.

FIG. 5B is a cross sectional view of the semiconductor device afterformation of a thin film 508 over the device. The thin film 508 isformed as described in block 404. The thin film 508 covers the firstpassivation layer 506 and portions of the TME layer 504.

A spacer etch is performed at block 406 to selectively remove portionsof the thin film and leave modulation spacers. The modulation spacersare formed on edges or sidewalls of the first passivation layer and mayalso be referred to as tapered portions of the thin film. The modulationspacers have a spacer angle, typically larger than about 100 degrees.Additionally, there is a via distance between the spacers and on the TMElayer.

The spacer etch, in one example, utilizes a selective etch rate betweenthe thin film and the first passivation layer. The etch removes the thinfilm from a surface of the first passivation layer and a portion of theTME layer. As a result, the modulation spacers are formed.

FIG. 5C is a cross sectional view illustrating the semiconductor deviceafter formation of modulation spacers 510. It can be seen that the thinfilm 508 shown in FIG. 5B is substantially removed leaving the spacers510. The film 508 was removed via the etch described in block 406.

The modulation spacers 510 are formed having a taper step angle 512 anda via width/distance ‘b’. The spacers 510 have a spacer height ‘a’,which also matches a height of the first passivation layer 506. Thesevalues can vary upon implementation.

In one example, the via width ‘b’ is about 2 um. The aspect ratio b/a isabout 2 to 5. The taper step angle is greater than about 100 degrees.

A metal layer is formed over the device at block 408. The metal layer isformed by a suitable metal deposition process, such as sputtering, andthe like. The metal layer includes a metal material, such as AlCu, inone example. The modulation bars and tapered portions of the hardmasklayer facilitate forming the metal layer properly, in particular withina via region.

FIG. 5D is a cross sectional view of the semiconductor device afterformation of a metal layer 514. In this example, the metal layer 514 iscomprised of AlCu and is formed as described in block 408. It can beseen that portions of the metal layer 514 extend to a surface of the TMElayer 504, to the first passivation layer 506 and to the modulationspacers 510.

The metal layer is patterned using a layer of resist to form aconductive via at block 410. A layer of resist is formed and utilizedwith a suitable patterning process to remove portions of the metallayer. The remaining portion forms the conductive via. A suitable metalpatterning process is utilized. It is appreciated that other suitablepatterning processes can be utilized.

FIG. 5E is a cross sectional view of the semiconductor device afterpatterning the metal layer 514. The remaining portion of the metal layer514 is a conductive via. A layer of resist used to pattern the metallayer 514 has been removed.

A second passivation layer is formed over the device at block 412. Thesecond passivation layer is also comprised of a suitable passivationmaterial, such as silicon nitride. The passivation layer forms over theconductive via with a suitable or enhanced coverage rate. As a result,the passivation layer protects the underlying layers, including theconductive via.

In contrast, other techniques to form such passivation layers overconductive vias result in poor coverage and result in gaps in thepassivation layer. The use of the modulation spacers mitigate creationof voids or gaps within the conductive via. The voids or gaps preventproper formation of the passivation layer and permit damaging ofunderlying layers.

FIG. 5F is a cross sectional view of the semiconductor device afterformation of a second passivation layer 516. It can be seen that thesecond passivation layer 516 covers all or substantially all portions ofthe remaining metal layer 514.

It is appreciated that suitable variations of the method 200 and 400 arecontemplated.

It will be appreciated that while reference is made throughout thisdocument to exemplary structures in discussing aspects of methodologiesdescribed herein (e.g., the structure presented in above figures, whilediscussing the methodology set forth in above), that those methodologiesare not to be limited by the corresponding structures presented. Rather,the methodologies (and structures) are to be considered independent ofone another and able to stand alone and be practiced without regard toany of the particular aspects depicted in the Figs.

Also, equivalent alterations and/or modifications may occur to thoseskilled in the art based upon a reading and/or understanding of thespecification and annexed drawings. The disclosure herein includes allsuch modifications and alterations and is generally not intended to belimited thereby. For example, although the figures provided herein, areillustrated and described to have a particular doping type, it will beappreciated that alternative doping types may be utilized as will beappreciated by one of ordinary skill in the art.

A semiconductor device having enhanced passivation integrity isdisclosed. The device includes a substrate, a first layer, and a metallayer. The first layer is formed over the substrate. The first layerincludes a via opening and a tapered portion proximate to the viaopening. The metal layer is formed over the via opening and the taperedportion of the first layer. The metal layer is substantially free fromgaps and voids. The first layer is a hardmask layer in one example. Thefirst layer is a passivation layer in another example.

Another semiconductor device having enhanced passivation integrity isdisclosed. The device includes a substrate, a hardmask layer, and ametal layer. The hardmask layer is formed over the substrate. Thehardmask layer includes a via opening, a tapered portion proximate tothe via opening, and modulation bar openings within the tapered portion.The metal layer is formed over the via opening and the tapered profileof the hardmask layer. The metal layer is substantially free from gapsand voids.

A method of fabricating a semiconductor device is disclosed. A substrateis provided. A first layer is formed over the substrate. A via openingand modulation bar openings are formed in the first layer. A taperedportion of the first layer about the modulation bar openings isgenerated. A metal layer is formed over the device using the taperedportion, the modulation bar openings, and the via openings. The metallayer is substantially free from gaps and voids.

Another method of fabricating a semiconductor device is disclosed. Asubstrate is provided. A hardmask layer is formed over the substrate. Avia opening and modulation bar openings are formed in the hardmasklayer. A tapered profile or portion is generated on the hardmask layerabout the modulation bar openings. A metal layer is formed over thedevice using the tapered profile, the modulation bar openings and thevia opening. The metal layer is substantially free from gaps and voids.

A method of fabricating a semiconductor device is disclosed. A substrateis provided. A first passivation layer is formed over the substrate. Ahardmask layer is formed over the substrate. A via opening andmodulation bar openings are formed in the hardmask layer. A metal layeris formed over the device using the modulation bar openings. The metallayer is substantially free of voids. The metal layer is patterned toform a conductive via. A second passivation layer is formed over theconductive via. The second passivation layer is free from gaps.

Another method of fabricating a semiconductor device is disclosed. Asubstrate is provided. A first layer is formed over the substrate. Thefirst layer is patterned to define an opening. A thin film is formedover the device. A spacer etch is performed to remove portions of thethin film and leave modulation spacers at sidewalls of the opening. Ametal layer is formed over the device using the modulation spacers tomitigate formation of gaps in the metal layer.

While a particular feature or aspect may have been disclosed withrespect to only one of several implementations, such feature or aspectmay be combined with one or more other features and/or aspects of otherimplementations as may be desired. Furthermore, to the extent that theterms “includes”, “having”, “has”, “with”, and/or variants thereof areused herein, such terms are intended to be inclusive in meaning—like“comprising.” Also, “exemplary” is merely meant to mean an example,rather than the best. It is also to be appreciated that features, layersand/or elements depicted herein are illustrated with particulardimensions and/or orientations relative to one another for purposes ofsimplicity and ease of understanding, and that the actual dimensionsand/or orientations may differ substantially from that illustratedherein.

What is claimed is:
 1. A semiconductor device, comprising: a substrate;a layer disposed over the substrate and including an opening extendingthrough the layer, the opening being laterally bound by inner sidewallsof the layer; a plurality of bar or pillar structures arranged in aperipheral portion of the opening and collectively laterally surroundinga central portion of the opening; and a metal body extending through theopening to separate neighboring bar or pillar structures within theplurality of bar or pillar structures from one another.
 2. Thesemiconductor device of claim 1, wherein the plurality of bar or pillarstructures and the layer have the same material composition.
 3. Thesemiconductor device of claim 1: wherein the central portion of theopening has a first lateral distance defined between an inner sidewallof a first bar or pillar structure, which is nearest the central portionof the opening and arranged on a first side of the central portion ofthe opening, and an inner sidewall of a second bar or pillar structure,which is nearest the central portion of the opening and arranged on asecond opposite side of the central portion of the opening; and whereinnearest sidewalls of neighboring bars or pillars on the first side orsecond side are separated by a second lateral distance which is lessthan the first lateral distance.
 4. The semiconductor device of claim 3,wherein the first lateral distance is at least three times greater thanthe second lateral distance.
 5. The semiconductor device of claim 3,wherein the first lateral spacing is greater than approximately 2micrometers and the second lateral spacing is greater than approximately0.5 micrometers.
 6. The semiconductor device of claim 1, wherein theplurality of bar or pillar structures have a plurality of lateralwidths, respectively, which are substantially equal to one another. 7.The semiconductor device of claim 6, wherein the plurality of bar orpillar structures have a plurality of lengths, respectively, and whereinat least two of the plurality of lengths differ from one another.
 8. Thesemiconductor device of claim 7, wherein two or more of the plurality ofbar or pillar structures have two or more lengths, respectively, whichare proportional to respective distances from a center of the centralportion of the opening to the two or more of the plurality of bar orpillar structures, respectively.
 9. The semiconductor device of claim 1,wherein the layer comprises a nitride or silicon dioxide layer.
 10. Thesemiconductor device of claim 1, wherein the plurality of bars or pillarstructures have upper surfaces that are substantially co-planar with oneanother and which are substantially co-planar with an upper surface ofthe layer.
 11. The semiconductor device of claim 1, wherein an innermostbar on one side of the central opening has a first height, and anoutermost bar on the one side of the central opening has a second heightthat differs from the first height.
 12. The semiconductor device ofclaim 11, wherein the plurality of bar or pillar structures have aplurality of heights, respectively, which monotonically increase fromthe innermost bar to the outermost bar.
 13. The semiconductor device ofclaim 1, further comprising: another layer conformally disposed over anupper surface and sidewall regions of the metal body.
 14. Asemiconductor device, comprising: a substrate; a first layer disposedover the substrate; a second layer disposed over the first layer anddiffering in material composition from the first layer; and a metal bodydisposed over the second layer and including a central portion and aperipheral portion which extend downwardly through the first and secondlayers, wherein the central portion has a first lateral width acrosswhich the metal body is continuous, and wherein the peripheral portionhas a plurality of ridges or pillars laterally separated from oneanother by a plurality of pillar or bar structures, respectively,wherein the pillar or bar structures collectively laterally surround thecentral portion of the metal body.
 15. The semiconductor device of claim14, further comprising: a third layer conformally disposed over an uppersurface and sidewall regions of the metal body.
 16. The semiconductordevice of claim 14: wherein an innermost pillar or bar structure nearestone side of the central portion of the metal body has a first height,and an outermost pillar or bar structure on the one side of the centralopening has a second height that differs from the first height; andwherein the plurality of pillar or bar structures have a plurality ofheights, respectively, which monotonically increase from the innermostpillar or bar structure to the outermost pillar or bar structure.
 17. Asemiconductor device, comprising: a substrate; a conductive layer overthe substrate; a first layer disposed over the conductive layer, thefirst layer having an opening which extends through the first layer andwhich is laterally bound by inner sidewalls of the first layer; atapered region disposed on the conductive layer along the innersidewalls of the first layer but leaving a surface region of theconductive layer exposed; and a metal body disposed over the taperedregion and over the first layer and extending downwardly between thetapered region to abut the surface region of the conductive layer. 18.The semiconductor device of claim 17, further comprising: a passivationlayer conformally disposed over an upper surface and sidewalls of themetal body.
 19. The semiconductor device of claim 17, wherein thetapered region has a sidewall angle of greater than about 100 degrees asmeasured from the surface region of the conductive layer to a sidewallof the tapered region.
 20. The semiconductor device of claim 17, whereinthe conductive layer has outer sidewalls that are spaced apart by afirst distance, and the inner sidewalls of the first layer are spacedapart by a second distance that is less than the first distance.